textproduct: Rapid City

KEY MESSAGES

- Slight Risk (level 2 of 5) of severe weather over western SD today with main threats being large hail and damaging winds. Low risk for isolated tornadoes. However, thunderstorm chances look widely scattered to isolated. Best chances NW toward central SD.

- Thick mid and high level smoke will spread into the region today from wildfires in Colorado and Utah.

- Another Slight Risk of severe weather for Friday, mainly over southern South Dakota.

- At or above normal highs continue with highs in the 80s to 90s through the weekend into next week.

UPDATE

Issued at 925 PM MDT Wed Jul 1 2026

Messy/difficult forecast the next couple days with several conditional items driving convection chances. Forecast models (esp hires models) have been all over the place with convective forecasts Thur and Friday with little to no continuity. There are some synoptic clues that help give an idea of what is expected though, with a couple impulses driving things. Shortwave moving across MT will turn east into ND overnight with a trailing sfc trough. This trough will be the focus for CI Thur, with convection likely initiating somewhere over NW SD/SW ND in the afternoon with additional convection possible in scentral SD INVOF of the trough. Further west, moisture will be much more depleted. Secondary impulse will move in WY later in the afternoon with high based convection possible across NE WY. This convection will shift east and may hold together once it gets into western SD. Main threat from this convection will be gusty winds while storms to the east will have a better chances for large hail and damaging winds. Severe threat is highly conditional Thur with the best chances for severe storms more toward the deeper moisture (and resultant CAPE) in eastern FA and central SD. Then to throw a wrench in the forecast, thick mid and high level smoke will spread north into the region from wild fires in CO and UT. This could highly impact temps and resulting mixing, inhibiting convection to a degree. Have added haze to the forecast for this and lowered highs some. As for Friday, a trough/boundary will settle into the area from the east and stall across the SW. At least that is the scenario attm. It is certainly possible this boundary could drop further south out of the FA. This boundary will be focus for CI Friday afternoon when the next impulse shifts east with upscale growth of cells possible with sufficient CAPE and marginal deep layer shear. Lingering storm chances Sat over the Hills if enough moisture lingers, but of an isolated nature. Unsettled next week.

DISCUSSION

(This Evening Through Wednesday) Issued at 209 PM MDT Wed Jul 1 2026

Latest satellite imagery has developing clouds over the Black Hills with a few returns on radar. Earlier we were watching smoke move over the area but it looks like now the smoke has moved east and mostly out of the CWA., That being said, those in south- central South Dakota are still stuck on the smoke and may be stuck under the smoke for a few more hours.

For later this afternoon through tonight, isolated shower and thunderstorm development is still possible but with the atmosphere not really set up to support storms, we aren't expecting the storm cells to last long once they track outside the Hills. This is idea supported by the last several runs of the HRRR and NamNEST.

For Thursday and Friday, general low pressure on the lee side of the Rockies will lead to thunderstorms in the plains. Also, a passing low pressure tracking eastward through southern Canada will also be a source of thunderstorms in the plains. On the front side of the general low pressure, thunderstorms are expected to develop, and that would include NE WY and W SD. These storms look to pop up in the heat of the day over the mountains and track northeast. Late Thursday into Thursday night, a cold front pushing through from the north, associated with the low pressure center in Canada, will be a trigger for more thunderstorms to develop in North Dakota and those storms will track southeast. Then on Friday, continued southwest flow will likely develop more thunderstorms Friday afternoon and those will track east to northeast into Friday night.

Sever weather is likely in those rounds of storms with large hail and strong winds being the main concerns for the CWA. Isolated tornadoes can't be completely ruled out but it's a small enough risk, around 2%, that the other storm modes are more concerning. The SPC has placed a Slight Risk over the area both Thursday and Friday.

The weekend is looking like a story with two very different chapters. Surface low pressure on the lee side of the Rockies will finally kick out eastward as an upper level trough slides eastwards along the northern edge of a high pressure building to our south. Once that trough and surface low move out, the ridge of high pressure will build over the CWA for Sunday.

This pattern will give the area storm chances Saturday into Saturday evening with afternoon temps in the 80s to near 90F. If we see any severe weather on Saturday, the latest guidance from today is putting the better chances of severe weather, around 15 to 30%, to the south in Nebraska and to the east closer to Iowa. So as of this writing, western South Dakota has a less than 15% chance to see severe weather on Saturday. Still worth keeping up on updates.

Sunday is looking very different as that high pressure builds. Skies will be clear to mostly clear and dry as afternoon temps jump into the 90s to near 100F.

A quick glance at next week, the near daily chances for isolated to scattered afternoon thunderstorms continue. Temperatures will be at or above normal with highs in the 80s to 90s and overnight lows in the 60s.

AVIATION

(For the 12Z TAFS Through 12Z Friday Morning) Issued At 548 AM MDT Thu Jul 2 2026

VFR conditions are generally expected throughout the forecast period into Friday morning. Main concern will be isolated to scattered thunderstorms initiating over the northern Black Hills region between 19-21z/1-3pm this afternoon, with that chance of storms then covering the entire forecast area through about sunset. Some of these storms may be severe with damaging winds, large hail, and an isolated tornado. Best storm coverage and intensity may favor South Dakota vs. northeastern Wyoming. Transient MVFR conditions cannot be ruled out underneath storm cores, but confidence in if and when a core may impact a given terminal is low. Have maintained a PROB30 for KRAP with an earlier start time based on the latest high-res guidance/CAMs. The HREF ensemble max wind gusts are quite impressive with some of these storms and forecast soundings include ample DCAPE, so have added VRB25G40KT with the PROB30. A lull may occur right after sunset, but some guidance suggests additional overnight convection is possible into early Friday morning, with low confidence on timing and location.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.